Astm d 1744 13

Designation D1744 − 13 An American National Standard Standard Test Method for Determination of Water in Liquid Petroleum Products by Karl Fischer Reagent1 This standard is issued under the fixed desig[.]

Designation: D1744 − 13 An American National Standard Standard Test Method for Determination of Water in Liquid Petroleum Products by Karl Fischer Reagent1 This standard is issued under the fixed designation D1744; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision A number in parentheses indicates the year of last reapproval A superscript epsilon (´) indicates an editorial change since the last revision or reapproval This standard has been approved for use by agencies of the U.S Department of Defense react with iodine, interfere One part per million of sulfur as mercaptan causes an error in the titration, equivalent to approximately 0.2 mg/kg of water Scope 1.1 This test method covers the determination of water in the concentration from 50 to 1000 mg/kg in liquid petroleum products Apparatus 1.2 Values stated in SI units are to be regarded as the standard Inch-pound units are provided for information only 1.3 This standard does not purport to address all of the safety problems, if any, associated with its use It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use For specific precautionary statements see Section 6.1 Assemble the apparatus as described in the Annex A1 (See Note 1.) NOTE 1—Any apparatus that will give equal or better precision is acceptable Reagents and Materials 7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available.3 Other grades can be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination Referenced Documents 2.1 ASTM Standards:2 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products Summary of Test Method 7.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean distilled water or water of equal purity The solvents used must have low-water content, for example, less than 500 mg/kg mass 3.1 The material to be analyzed is titrated with standard Karl Fischer reagent to an electrometric end point Significance and Use 4.1 Knowledge of the water content of petroleum products can be useful to predict quality and performance characteristics of the product 7.3 Karl Fischer Reagent, Solution (Note 2), Stock— (Warning—Toxic.) For each litre of solution, dissolve 85 g of iodine in 270 mL of pyridine in a dry, glass-stoppered bottle Add 670 mL of methanol (99.9 %) (Note 3) Cool the mixture in an ice bath to below 3.9°C Bubble gaseous sulfur dioxide (SO2) (Note 4) through concentrated sulfuric acid (H2SO4, rel dens 1.84) (see warning information below) into the cooled mixture Continue the addition of SO2 until the volume is increased 50 mL Alternatively, add 50 mL of freshly drawn liquid SO2 in small increments to the precooled mixture in an ice bath Mix well and set aside for at Interferences 5.1 Free alkali, oxidizing and reducing agents, mercaptans, certain basic nitrogenous substances, or other materials that This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee D02.02 on Hydrocarbon Measurement for Custody Transfer (Joint ASTM-API) Current edition approved Dec 1, 2013 Published December 2013 Originally approved in 1960 Last previous edition approved in 1992 as D1744 – 92, which was withdrawn in January 2000 and reinstated in December 2013 DOI: 10.1520/ D1743-13 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S Pharmaceutical Convention, Inc (USPC), Rockville, MD Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959 United States D1744 − 13 9.1.5 From a tared weighing bottle, by means of a clean, dry spatula, transfer approximately 250 mg of sodium tartrate dihydrate to the pretitrated alcohol in the titration flask Record the mass 9.1.6 Dip the spatula into the solvent to ensure the removal of any adhering tartrate (Note 3) Stopper the flask and titrate to the end point as described in 9.1.1 least 12 h before using (Warning—Poison Corrosive Strong oxidizer Contact with organic material can cause fire Can be fatal if swallowed Liquid and vapor can cause severe burns Harmful if inhaled Contact with water liberates large amounts of heat Spillage can cause fire.) NOTE 2—Commercially prepared Karl Fischer Reagent may be used NOTE 3—If 99.9 % methanol is not commercially available, it can be prepared by dissolving 24 g of magnesium metal turnings in 200 mL of methanol Caution, the reaction is vigorous When the reaction is complete, add L of methanol Reflux for h and distill directly into the container in which the 99.9 % methanol is to be kept Vent the system through a drying tube during the distillation NOTE 4—Follow standard safety precautions for handling toxic gases NOTE 5—To facilitate transferal of the tartrate to vessels having constricted openings or narrow necks, a spatula with the tip bent at a right angle to the handle is satisfactory 9.1.7 Determine the total water content of the sodium tartrate dihydrate by drying a preweighed sample to a constant mass in an oven at 150 5°C 9.1.8 Calculate the water equivalence of the Karl Fischer reagent as follows: 7.4 Karl Fischer Reagent, Dilute Solution—Adjust the strength of the stock solution to a water equivalence of to mg of water per mL by dilution with pyridine F ~ A B ! ⁄100T 7.5 Sample Solvent—Mix volume of methanol (Note 4) with volumes of chloroform (Warning—Can be fatal if swallowed Harmful if inhaled Can produce toxic vapors if burned.) where: F = the water equivalence of Karl Fischer reagent, mg/ mL, A = milligrams of sodium tartrate dihydrate used, B = percentage of water in the sodium tartrate dihydrate, and T = millilitres of reagent required for titration of the water in the sodium tartrate dihydrate Sampling 8.1 Take samples in accordance with the instructions in Practice D4057 Standardization of Karl Fischer Reagent 10 Procedure 9.1 The dilute Karl Fischer reagent should be standardized at least daily in accordance with either 9.1.1 to 9.1.3 or 9.1.4 to 9.1.8 9.1.1 Add 50 mL of the sample solvent to a clean, dry titration flask Insert the stopper and adjust the magnetic stirrer to give a smooth stirring action Turn on the indicating circuit and adjust the potentiometer to give a reference point with approximately µA of current flowing Add Karl Fischer reagent in suitable amounts to the solvent to cause the needle to deflect from the reference point At first the needle will deflect due to local concentration of the unreacted reagent about the electrodes but will fall back to near the reference point As the end point is approached, the needle will fall back more slowly after each addition of Karl Fischer reagent The end point is reached when, after the addition of a single drop of reagent, the needle remains deflected at least µA from the reference point for at least 30 s 9.1.2 To the solution in the titration flask add carefully, from a weighing pipet previously weighed to the nearest 0.1 mg, drop of distilled water Stopper the flask Reweigh the weighing pipet Titrate to the end point as described in 9.1.1 9.1.3 Calculate the water equivalence of the Karl Fischer reagent as follows: F W⁄T (2) 10.1 Add 50 mL of solvent to the titration flask and titrate with standardized Karl Fischer reagent to the end point as described in 9.1.1 It is important to stopper the sample inlet tube as quickly as possible to prevent absorption of moisture from the atmosphere 10.2 Obtain a hydrometer reading on the material to be tested and convert degrees API to relative density without correcting for temperature Immediately pipet 50 mL of the sample into the titration flask Alternatively, the sample can be weighed and added to the titration flask in any convenient manner 10.3 Titrate the sample to the end point as described in 9.1.1 Record the millilitres of reagent used 11 Calculation or Interpretation of Results 11.1 Calculate the water content of the sample as follows: Water, mg/kg =~ C F 1000! ⁄ @ W or A G! # (3) where: C = millilitres of reagent required for titration of the sample, F = water equivalence, milligrams mg water/mL, 1000 = factor for converting to parts per million, W = grams of sample used = A × G, A = millilitres of sample used, and G = relative density of the sample (1) where: F = water equivalence of Karl Fischer reagent, mg/mL, W = milligrams of water added, and T = millilitres of reagent required for titration of the added water 12 Precision and Bias 12.1 The precision of this test is not known to have been obtained in accordance with currently accepted guidelines (for example, in Committee D02 research report RR:D02-1007, Manual on Determining Precision Data for ASTM Methods on 9.1.4 Alternatively, add 50 mL of methanol as the titration solvent to the titration flask and titrate to the end point as described in 9.1.1 D1744 − 13 Petroleum Products and Lubricants).2 These results apply only to aviation turbine fuel Difficulties encountered in distributing stable samples have prevented development of additional data Water Content, µg/g 50 to 1000 Repeatability, µg/g 11 12.2.2 Reproducibility—The reproducibility of the method has not been determined because of the difficulty encountered in maintaining sample integrity when distributing them to the cooperator’s laboratories 12.2 The precision of the method as obtained by statistical examination of interlaboratory test results is as follows: 12.2.1 Repeatability—The difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method exceed the following values only one case in twenty: 12.3 Bias—The bias of this test method has not been determined 13 Keywords 13.1 Karl Fischer; petroleum products; water ANNEX (Mandatory Information) A1 APPARATUS A1.2.2 Battery—A 1.5-V dry cell A1.1 Titration Assemblies—The titration assembly (Fig A1.1) shall include the following: A1.2.3 Electrodes—Suitable electrodes (Fig A1.2) can be constructed as follows: Seal a piece of platinum wire approximately 25 mm (1 in.) in length (diameter of wire 0.3 to 0.8 mm (0.01 to 0.03 in.)) into a piece of small bore soft glass tubing approximately 160 mm long Approximately 7.1 mm (0.28 in.) of the wire should extend above the seal on the inside of the tubing and approximately 15.2 mm (0.60 in.) extend outside the seal Bend the glass tubing slightly about 20 to 30 mm above the seal as shown in Fig A1.2 Make a small loop approximately 6.4 mm (0.25 in.) in diameter in the end of the platinum wire Place sufficient mercury in the glass tube to provide contact for the leads to complete the circuit Two electrodes are required Care should be exercised that cracks not develop around the seal, which will make the electrodes useless A1.1.1 Buret—A 10-mL buret graduated 0.05-mL subdivisions and fitted within a three-way stopcock Some stopcock greases are affected by Karl Fischer reagent A1.1.2 Reagent Reservoir—Any convenient-size glass bottle A1.1.3 Stirrer—Magnetic stirrer A1.1.4 Titration Flask—A three-neck flask of approximately 500-mL capacity A1.1.5 Assemble the apparatus as shown in Fig A1.1 All possible precautions must be taken to prevent absorption of moisture from the atmosphere Cracks between glass and stoppers should be sealed with a suitable sealing material and necessary openings should be protected by the use of drying tubes containing anhydrous calcium sulfate A1.2.4 Potentiometer—A potentiometer having a resistance of 2000 Ω A1.2 Electrical Circuit—The electrical circuit (Fig A1.1) shall include the following: A1.2.5 Assemble the circuit as shown in Fig A1.1 A1.2.1 Microammeter—A d-c microammeter having a range from to 50 µA and an internal resistance of approximately 1500 Ω D1744 − 13 FIG A1.1 Apparatus for Determination of Water by Karl Fischer Reagent D1744 − 13 FIG A1.2 Electrode ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above address or at 610-832-9585 (phone), 610-832-9555 (fax), or service@astm.org (e-mail); or through the ASTM website (www.astm.org) Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http://www.copyright.com/